LIGO Document P170608-v12

On 2017 June 8 at 02:01:16.49 UTC, a gravitational-wave signal from the merger of two stellar-mass black holes was observed by the two Advanced LIGO detectors with a network signal-to-noise ratio of 13. This system is the lighest black hole binary so far observed, with component masses 12+7−2M☉ and 7+2−2M☉ (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through gravitational waves with electromagnetic observations. The source's luminosity distance is 340+140−140M☉ Mpc, corresponding to redshift 0.07+0.03−0.03M☉. We verify that the signal waveform is consistent with the predictions of general relativity.